As a technology for guiding light which is incident on a window pane to the inside of a house with high efficiency, a technology disclosed in PTL 1 has been known. In the technology disclosed in PTL 1, a lighting sheet obtained by forming a plurality of prism units on one surface of a transparent support base adheres to an external surface (surface on the outside of a house) of a window pane so as to cause the prism unit side to be directed toward the outside of a house. Light which is incident from the prism unit side is refracted by a surface of the prism unit, passes through the prism unit, the support base, and the window pane, and then the light is incident to the inside of the house.